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1. Developer clones component repository from Gerrit server https://code.rdkcentral.com/r/ into local workspace.

$ git clone https://user@code.rdkcentral.com/r/component1

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Example commands to run are as follows:

$ git config user.name "John Doe"
$ git config user.email "john.doe@example.org"

2. Set up the commit-msg hook to add Change-ID footer to commit messages.

The commit-msg hook is installed in the local Git repository and is a prerequisite for Gerrit to accept commits. The inclusion of the unique Change-ID in the commit message allows Gerrit to automatically associate a new version of a change back to its original review.

Note: To download the commit-msg script from the Gerrit server to your local system use and make the hook file executable:

$ cd <path_to_git_checkout>
$ curl -o <local path to your git>/ .git/hooks/commit-msg <your Gerrit https URL>msg https://code.rdkcentral.com/r/tools/hooks/commit-msg
$ chmod u+x ~/component1/ .git/hooks/commit-msg

3. Developer works on the change, committing to local clone.The Developer creates a topic branch in the local work area, makes the necessary changes and then squashes the commits prior to pushing for review.
Note: To create a topic branch use:

git checkout -b <Branch Name>

Each commit constitutes a change in Gerrit and must be approved separately. It is recommended to squash several commits into one that represents a change to the project. It

If necessary, it is possible to squash a series of commits into a single commit before publishing them, using interactive rebase `git :

$ git rebase --

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interactive

It is important to preserve the Change-Id line when editing and there should only be one "pick" entry at the end of this process. The end result is to submit one change to Gerrit.

4. Developer pushes the new change to Gerrit for review, i.e. to refs/for/master.

$ git push origin HEAD:refs/for/master

When interfacing with Gerrit you push to a virtual branch , /refs/for/<branch>, representing "code review before submission to branch". Gerrit will subsequently assign a unique URL for the change, to facilitate access and review via the web UI.

NoteNotes: HEAD  

• HEAD is a

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• Git symbolic reference to the most recent commit on the current branch. When you change branches, HEAD is updated to refer to the new branch's latest commit.

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• The refspec in the git push operation takes the form source:destination (source is the local ref being pushed, destination is the remote ref being updated).

5. Review notifications and addition of new reviewers.

The Developer may request feedback by adding additional reviewers via the Gerrit web GUI or alternatively by specifying details on the command line when pushing changes to Gerrit. Component owners/reviewers/approvers, defined as specific groups in the external LDAP system, will be added by default.

Note: additional  Optionally, additional reviewers can be added using ``%r=user@mail.com`` syntax during the push operation on the command line.

6. Run BlackDuck, copyright scanning and build on code submission.

If applicable, BlackDuck, copyright scanning and build jobs will be triggered automatically from CMF Jenkins. The output of these jobs is integrated into the Gerrit voting process via custom labels and will reflect any 'red flag' in a file that has new code changes, whether introduced in the new Change/Patch Set change/patch-set or not.

7. Code review and scoring process

Reviewers can comment on and score a given change.
The default set of rules for enabling a code change for submission requires:

• a Code Review score of +2

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• ; this can only be provided by the component owner or an admin;
• +1 score on any mandatory Gerrit labels configured for the project.

The result of the scoring process and validation rules is to enable the Submit action on the Gerrit Web UI and subsequent merge capability to the target branch.

Label: Code Review For a change to be submissiblemergeable, the latest patch set must have a '+2' value approval in this category or label, and no '-2 Do not submit'. Thus -2 on any patch set can block a submit, while +2 on the latest patch set can enable enables it for merging.

Labels: Blackduck/Copyright/Component-Build For a change to be submissiblemergeable, the change must have a '+1' score on these labels, and no '-1 Fails'. Thus, '-1 Fails' can block a submit, while '+1' enables a submit.

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8. Submit change

Only authorised users, i.e. component owners and , component approvers or admins, can submit the change allowing Gerrit to merge it to the target branch as soon as possible. A change can be submitted, having satisfied the approval conditions described earlier, by clicking the 'Submit Patch Set n' button within the Gerrit UI.

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11. Change needs to be reworkedRebase and amend the commit and push to `refs/for/<target branch>` again.

In order to submit a reworked change it is necessary to push another commit that has the same Change-ID (as  as the original ) in the message.
This is the mechanism Gerrit uses to associate or link the two items. The `--amend` option to git commit prevents a new Change-ID being generated by the commit-msg hook.

The basic steps are outlined below:.

First, fetch the change. If you still have the checkout that was used to push the original change, you can skip this step.

$ git fetch https://user@code.rdkcentral.com/r/component1 refs/changes/02/2/1 && git checkout FETCH_HEAD

where the numbering scheme for fetching the changes is as follows:

refs/changes/<last two digits of change number> <change number> <patch set number>

Note: Gerrit will specify this fetch URL via the web UI on the 'Download' link on the review page for the change in question, the developer just pastes it into the command line.

Next, make any necessary source changes, and do:

$ [Edit the file]
git commit --amend
$ git push origin HEAD:refs/for/master

A new patch set is now appended to the Gerrit review item, and this will go through the same review process as before.

Note: The 'change number' referenced above is different to underlying Git commit ID.
Note: Patch-sets are numbered (starting from 1) for each review, and incremented whenever a change is amended with another Git commit.
Note: FETCH FETCH_HEAD is a Git symref symbolic reference and shorthand for the head of the last branch fetched and is valid only immediately after the fetch operation.

12. Automatic merge of changeset to target branch after successfully submittingWhen a change has been Submitted, it is automatically merged to the target branch by Gerrit.

13. Gerrit merge failure as a result of a conflict

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Note: If the local branch no longer exists, the steps are as follows :

git checkout -b topic_branch
$ git fetch https://user@code.rdkcentral.com/r/rdk_component_1 refs/changes/58/58/2 && git checkout FETCH_HEAD
$ git rebase origin/master
[Edit the conflicting file, cleaning up the <<<<, ==== >>> markers surrounding the conflicting lines]
$ git add <file>
$ git commit --amend
$ git push origin HEAD:refs/for/master